Silicone polymer emulsions

ABSTRACT

In a process for the preparation of an emulsion of a silicone organic block copolymer in water, a polydiorganosiloxane having terminal reactive groups (A), an organic material having terminal groups (B) which are reactive with the groups (A) and a catalyst are emulsified in water with a surfactant and the resulting emulsion is subjected to conditions under which the reaction between groups (A) and (B) proceeds in the presence of the catalyst, thereby forming a copolymer chain containing polysiloxane blocks and blocks of organic material. Preferred emulsions comprise a copolymer comprising polydiorganosiloxane blocks and organic blocks, having a viscosity in the range 10 to 1000000 Pa.s and a mean particle size of 0.3 to 1000 micrometers.

FIELD OF THE INVENTION

This invention relates to silicone in water emulsions and to methods ofmaking them.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 6,013,682-A describes a method of making a silicone inwater emulsion comprising mixing (I) a composition containing at leastone polysiloxane, at least one organosilicon material that reacts withsaid polysiloxane by a chain extension reaction and a metal containingcatalyst for said chain extension reaction, (II) at least one surfactantand (III) water to form a mixture; and emulsifying the mixture.

U.S. Pat. No. 5,973,068-A describes emulsion polymerizing asilanol-terminated resin and a vinyl monomer. Polymerization in theemulsion polymerization process occurs at the silicone water interfaceso that the rate of polymerization is faster with smaller particlesbecause of the larger surface area. Thus, it is impossible to producelarge particle size, high molecular weight silicone gum in wateremulsions by emulsion polymerisation.

U.S. Pat. No. 5,731,379-A describes copolymerisation of anacrylate-terminated polydimethylsiloxane and an acrylate-terminatedpolyisobutylene by free radical polymerisation. EP 872509-A describesreaction of an acrylate-terminated polydimethylsiloxane with anamine-terminated polyisobutylene.

U.S. Pat. No. 4,962,165-A describes the reaction of anorganohydrogen-polysiloxane with a multifunctional unsaturated monomerhaving unsaturated groups of different relativities such as allylmethacrylate. The allyl group reacts with Si—H groups and themethacrylate group subsequently undergoes free radical polymerisation.

SUMMARY OF THE INVENTION

In a process according to one aspect of the present invention for thepreparation of an emulsion of a silicone organic block copolymer inwater, a polydiorganosiloxane having terminal reactive groups (A), anorganic material having terminal groups (B) which are reactive with thegroups (A) and a catalyst are mixed and then emulsified in water with asurfactant and the resulting emulsion is subjected to conditions underwhich the reaction between groups (A) and (B) proceeds in the presenceof the catalyst, thereby forming a copolymer chain containingpolysiloxane blocks and blocks of organic material.

In a process according to another aspect of the invention for thepreparation of an emulsion of a silicone organic block copolymer inwater, a polydiorganosiloxane having terminal Si—H groups (A), anorganic material having terminal aliphatically unsaturated groups (B)which are reactive with the Si—H groups (A) and a catalyst areemulsified in water with a surfactant and the resulting emulsion issubjected to conditions under which the reaction between groups (A) and(B) proceeds in the presence of the catalyst, thereby forming acopolymer chain containing polysiloxane blocks and blocks of organicmaterial.

The emulsions produced by the process of this invention can have a widevariety of silicone copolymer concentrations, particle sizes andmolecular weights, including novel materials having high concentrationsof large particle silicone copolymer of high molecular weight. Moreover,the process results in emulsions in which the particle size and themolecular weight of the silicone inside the droplets are independentparameters. The particle size can for example be chosen within the range0.1 to 1000 micrometres.

A novel emulsion of a silicone organic copolymer in water according to afurther aspect of the present invention is characterised in that thecopolymer comprises polydiorganosiloxane blocks and organic blocks andhas a dynamic viscosity at 0.01 Hz in the range 10 to 1000000 Pas and amean particle size of 0.3 to 1000 micrometers. The silicone emulsioncopolymer preferably has dynamic viscosity of at least 1000 Pa.s. Suchhigh viscosities have to be measured as dynamic viscosity rather thanflow viscosity, and are measured at a low frequency such as 0.01 Hzbecause this has been found for less viscous silicones to correspondwell to flow viscosity.

DETAILED DESCRIPTION

The terminal reactive groups (A) in the polydiorganosiloxane arepreferably Si—H groups which can react with an aliphatically unsaturatedgroup in the presence of a platinum or rhodium containing catalyst. Thepolydiorganosiloxane is generally a substantially linear polymer andpreferably has the structure:

where R represents a hydrocarbon group having up to 20 carbon atoms suchas an alkyl (e.g., methyl, ethyl, propyl or butyl), or aryl (e.g.,phenyl) group and R′ represents the group required for the chainextension reaction with the organic material, for example hydrogenbonded to silica; and n is an integer greater than 1. The group R′ canalternatively contain a reactive organic group, for example it can be analiphatically unsaturated group such as vinyl, allyl or hexenyl or anaminoalkyl group. Preferably there is on average between one and tworeactive groups (inclusive) per polymer, most preferably two groups orjust less. Preferably, a majority, more preferably over 90%, and mostpreferably over 98% of the reactive groups are end-groups R′ as shown.Preferably n is an integer such that the polydiorganosiloxane has aviscosity between 1 and 1×10⁶ mm²/sec at 25° C.

If desired, the polydiorganosiloxane can have a small amount ofbranching (e.g., less than 2 mole % of the siloxane units) withoutaffecting the invention, i.e., the polymers are ‘substantially linear’.The groups R are usually hydrocarbyl groups, for example alkyl or arylgroups; preferably at least 80% of the R groups are alkyl groups, morepreferably methyl groups. If desired, R groups can be substituted with,for instance, oxygen containing groups such as epoxy or alcohol groups.

The organic material reacts with the polysiloxane by a chain extensionreaction and can be either a polymer or a non-polymeric material thatacts as a chain extension agent. The terminal reactive groups (B) of theorganic material are preferably aliphatically unsaturated groups, forexample vinyl or allyl groups. The organic material is preferably apolymer having a backbone of carbon—carbon bonds, for example anaddition polymer. Polymers whose repeating units have electron donorcharacteristics are particularly preferred, for example polyisobutylenehaving terminal unsaturation such as diallyl-endblockedpolyisobutylenes, which are available commercially with various chainlengths. Polyisobutylenes of molecular weight in the range 1000 to50000, preferably 2000 to 20000, can for example be used. The polymercan alternatively contain linkages comprising a heteroatom such as O orN, for example ether, ester, amide, imide or urethane linkages. Examplesof such polymers are polyoxyalkylene glycols etherified with anunsaturated group, such as polyethylene glycol divinyl ether, or anacrylate or methacrylate polymer such as a urethane acrylate.

A non-polymeric organic material for use in the process of the inventioncan for example be a non-conjugated diene, preferably an alpha,omega-diene having 6 to 30 carbon atoms such as 1,5-hexadiene or1,7-octadiene. The diene can have more than 30 carbon atoms but ispreferably liquid. Alternatively compounds containing two vinyl or allylgroups can be used, for example diallyl ether, diallyl amine, diallylcarbonate, diallyl phthalate, diallyl succinate, 1,3-diallyl urea, allylmethacrylate, propylene glycol divinyl ether or tetraethylene glycoldivinyl ether.

The organic material (B) can alternatively comprise a material havingthree reactive groups (B), e.g. three aliphatically unsaturated groups.This will lead to a branched or 3-limbed polymer, but it is generallypreferred to use a difunctional organic material to produce an emulsionof a linear copolymer.

The catalyst is preferably a metal-containing catalyst of a type knownfor chain extension reactions of siloxanes, for example a materialcontaining a metal such as platinum, rhodium, tin, titanium, copper orlead. A hydrosilylation catalyst for the reaction of an organosiliconmaterial having Si—H groups and an organic material having aliphaticallyunsaturated groups can be, for example, a platinum or rhodium containingmaterial. These catalysts may take the form of platinum or rhodiumdeposited on a carrier such as silica gel or powdered charcoal, or aplatinum or rhodium salt or compound such as platinic chloride orchloroplatinic acid or a platinum or rhodium complex. Catalystscomprising Pt^(IV), for example platinic chloride or chloroplatinicacid, or a complex prepared from chloroplatinic acid hexahydrate anddivinyltetramethyldisiloxane, are particularly preferred. Generally, thecatalyst is used at between 0.0001 and 10 wt. % based on the weight ofthe polydiorganosiloxane.

The surfactant can in general be a non-ionic surfactant, a cationicsurfactant, an anionic surfactant or an amphoteric surfactant, althoughnot all procedures for carrying out the process of the invention can beused with all surfactants. The amount of surfactant used will varydepending on the surfactant, but generally is between 1 and 30 wt. %based on the polydiorganosiloxane.

Examples of non-ionic surfactants include polyoxyalkylene alkyl etherssuch as polyethylene glycol long chain (12-14C) alkyl ether,polyoxyalkylene sorbitan ethers, polyoxyalkylene alkoxylate esters,polyoxyalkylene alkylphenol ethers, ethylene glycol propylene glycolcopolymers and alkylpolysaccharides, for example materials of thestructure R¹—O—(R²O)_(m)—(G)_(n) wherein R¹ represents a linear orbranched alkyl group, a linear or branched alkenyl group or analkylphenyl group, R² represents an alkylene group, G represents areduced sugar, m denotes 0 or a positive integer and n represents apositive integer as described in U.S. Pat. No. 5,035,832.

Examples of cationic surfactants include quaternary ammonium hydroxidessuch as octyl trimethyl ammonium hydroxide, dodecyl trimethyl ammoniumhydroxide, hexadecyl trimethyl ammonium hydroxide, octyl dimethyl benzylammonium hydroxide, decyl dimethyl benzyl ammonium hydroxide, didodecyldimethyl ammonium hydroxide, dioctadecyl dimethyl ammonium hydroxide,tallow trimethyl ammonium hydroxide and coco trimethyl ammoniumhydroxide as well as corresponding salts of these materials, fattyamines and fatty acid amides and their derivatives, basic pyridiniumcompounds, quaternary ammonium bases of benzimidazolines andpolypropanolpolyethanol amines.

Examples of suitable anionic surfactants include alkyl sulfates such aslauryl sulfate, polymers such as acrylates/C₁₀₋₃₀ alkyl acrylatecrosspolymer alkylbenzenesulfonic acids and salts such ashexylbenzenesulfonic acid, octylbenzenesulfonic acid,decylbenzenesulfonic acid, dodecylbenzenesulfonic acid,cetylbenzenesulfonic acid and myristylbenzenesulfonic acid; the sulfateesters of monoalkyl polyoxyethylene ethers; alkylnapthylsulfonic acid;alkali metal sulforecinates, sulfonated glyceryl esters of fatty acidssuch as sulfonated monoglycerides of coconut oil acids, salts ofsulfonated monovalent alcohol esters, amides of amino sulfonic acids,sulfonated products of fatty acid nitriles, sulfonated aromatichydrocarbons, condensation products of naphthalene sulfonic acids withformaldehyde, sodium octahydroanthracene sulfonate, alkali metal alkylsulfates, ester sulfates, and alkarylsulfonates.

Examples of suitable amphoteric surfactants include cocamidopropylbetaine, cocamidopropyl hydroxysulfate, cocobetaine, sodiumcocoamidoacetate, cocodimethyl betaine, N-coco-3-aminobutyric acid andimidazolinium carboxyl compounds.

The above surfactants may be used individually or in combination.

In one preferred process according to the invention, thepolydiorganosiloxane, the organic material, the catalyst and thesurfactant are mixed and are emulsified in water.

The polydiorganosiloxane, the organic material, the catalyst and thesurfactant can be mixed all at once or these materials can be mixed inany order. However when the polydiorganosiloxane, the organic materialand the catalyst are combined, the polymerisation reaction begins. Assuch, it may be preferred to mix one of these components of thecomposition last. For example, it may be preferred to premix the metalcontaining catalyst, the organic material and the surfactant beforemixing with the polysiloxane. Anionic surfactants may increase thekinetics of the chain extension reaction between a polydiorganosiloxanehaving at least one Si—H group and an aliphatically unsaturated organicmaterial in the presence of a hydrosilylation catalyst. The unsaturatedorganic material can be premixed with the catalyst and then mixed in amixture of the anionic surfactant and the polydiorganosiloxane (i.e.,the Si—H material). Alternatively, a cure inhibitor could be added tocontrol the reaction kinetics.

The polydiorganosiloxane, organic material, catalyst and surfactant canbe premixed with other materials which do not inhibit polymerisation,for example a solvent, plasticiser or filler. Such a material ispreferably lipophilic, that is it should have more affinity for thesiloxane and the organic material than for water. The organic materialand/or siloxane can be premixed with a hydrocarbon solvent, for exampletoluene, before contacting the surfactant to inhibit interaction withwater. A non-reactive silicone resin, for example a MQ resin comprisingtriorganosilyl units and SiO_(4/2) units and/or a hydrophobic filler,for example a treated silica, can be premixed with thepolydiorganosiloxane. A lipophilic active material such as a perfume,sunscreen or pharmaceutical additive can be premixed with the organicmaterial and/or the siloxane and will be carried by the oil phase of thecopolymer emulsion so that it is deposited with the copolymer, forexample on hair from a shampoo.

The resulting mixture can be mixed with water by simple agitation toform a coarse water in oil mixture. This mixture is then emulsified.During emulsification, the coarse water in oil mixture is inverted intoa fine silicone in water emulsion. After inversion, the chain extensionreaction continues within the silicone droplet until all the materialshave reacted or the reaction has been inhibited. The emulsification canbe accomplished by conventional means such as a batch mixer, colloidmill or line mixer. The emulsification process is simple and fast, andthis procedure can be used with any type of surfactant.

The quantity of water and/or surfactant used in the initial phaseinversion process may have an impact on the particle size of the finalemulsion. For instance, if an emulsion is formed with the same quantityof water in two instances but in the first a large quantity of water ismixed before the phase inversion step and in the second a small quantityof water is mixed before the phase inversion step followed by mixing theremaining additional water after the phase inversion step, the firstemulsion will generally have a larger particle size than the second. Nomatter how the water is added, the total amount of water used isgenerally between about 1 and 99 wt. %, preferably between about 6 andabout 99 wt. %, based on the weight of the emulsion.

Polymerisation in the above procedure takes place at the interior of theoil droplets by chain extension (i.e., not at the oil/water interface).The degree of polymerisation is not controlled by droplet size, but bythe ratio of materials used in the chain extension reaction. This allowsfor the production of a broad range of monodisperse droplet sizescontaining polysiloxanes with a high viscosity and, if required,emulsions with high silicone volume fractions.

In an alternative procedure according to the invention, thepolydiorganosiloxane and the organic material are emulsified in waterwith a surfactant and the catalyst is added to the emulsion. A nonionicsurfactant is preferred for this process since the presence of ionicsurfactant in the aqueous phase inhibits the catalysis of thehydrosilylation reaction by metal-containing catalysts such as PtIVcompounds.

In a third procedure according to the invention, thepolydiorganosiloxane and the organic material are emulsified in waterwith an anionic, cationic or amphoteric surfactant and the catalyst isdispersed in a nonionic surfactant before being added to the emulsion.The catalyst can simply be mixed with the nonionic surfactant and addedto the emulsion or the catalyst and nonionic surfactant can be premixedwith water before being added. Mixing with the nonionic surfactantavoids inhibition of the catalyst by the ionic surfactant. The amount ofnonionic surfactant used is preferably 0.1-10 parts per volume per partof a commercial platinum catalyst preparation (about 2-200 parts byweight per part of platinum in the catalyst). This procedure is usefulin preparing a silicone copolymer emulsion based on an anionic,amphoteric or cationic surfactant, for example for inclusion in apersonal care product such as a shampoo based on the same type ofsurfactant.

If desired, other materials can be added to either phase of theemulsions, for example perfumes, colorants, thickeners, preservatives,plasticisers or active ingredients such as pharmaceuticals.

The emulsions of the present invention can generally have a siliconeloading in the range of about 1 to about 94 wt. %. The molecular weightof the silicone can be in the range of that corresponding to a bulkviscosity of about 1 mm²/sec at 25° C. to in excess of 10⁸ mm²/sec at25° C., most preferably 10⁶ to 10⁸ mm²/sec. (1000-100000 Pa.s.). Themean particle size of the emulsion is preferably from 0.1 to 1000micrometers, more preferably about 0.3 to 100 micrometers. The emulsionsof the invention render the high molecular weight silicone in thedroplets easily handleable.

The emulsions of the invention are useful in most known applications forsilicone emulsions, for example in personal care applications such as onhair, skin, mucous membrane or teeth. In these applications, thesilicone is lubricious and will improve the properties of skin creams,skin care lotions, moisturisers, facial treatments such as acne orwrinkle removers, personal and facial cleansers, bath oils, perfumes,fragrances, colognes, sachets, sunscreens, pre-shave and after shavelotions, shaving soaps and shaving lathers. It can likewise be use inhair shampoos, hair conditioners, hair sprays, mousses, permanents,depilatories, and cuticle coats, for example to provide styling andconditioning benefits. In cosmetics, it functions as a levelling andspreading agent for pigment in make-ups, colour cosmetics, foundations,blushes, lipsticks, eye liners, mascaras, oil removers, colour cosmeticremovers and powders. It is likewise useful as a delivery system for oiland water soluble substances such as vitamins, organic sunscreens,ceramides, pharmaceuticals and the like. When compounded into sticks,gels, lotions aerosols and roll-ons, the emulsions of this inventionimpart a dry silky-smooth payout.

When used in personal care products, they are generally incorporated inamounts of about 0.01 to about 50 weight percent, preferably 0.1 to 25wt. percent, of the personal care product. They are added toconventional ingredients for the personal care product chosen. Thus,they can be mixed with deposition polymers, surfactants, detergents,antibacterials, anti-dandruffs, foam boosters, proteins, moisturisingagents, suspending agents, opacifiers, perfumes, colouring agents, plantextracts, polymers, and other conventional care ingredients.

Beyond personal care, the emulsions of the invention are useful fornumerous other applications such as textile fibre treatment, leatherlubrication, fabric softening, release agents, water based coatings, oildrag reduction, particularly in crude oil pipelines, lubrication,facilitation of cutting cellulose materials, and in many other areaswhere silicones are conventionally used. The silicone organic copolymershave particular advantages in oil drag reduction resulting fromincreased compatibility with hydrocarbon fluids.

The following Examples are provided so that one skilled in the art willmore readily understand the invention. Unless otherwise indicated, allparts and percents are by weight and all viscosities are at 25° C.

EXAMPLE 1

25 parts of a Si—H terminated polydimethylsiloxane having a viscosity of60000 mm²/sec was mixed with 2.5 parts “Kaneka Epion 200A” (Trade Mark)allyl end blocked polyisobutylene of molecular weight 5000 and thenstirred with 0.35 parts Pt^(IV) catalyst (a chloroplatinic acid complexcontaining 4% platinum). 1.7 parts “Laureth 23” and 1.25 parts“Laureth-3” (nonionic polyethylene glycol lauryl ether surfactants ofdifferent chain lengths) were stirred in and 1 part water was added withstirring to invert the mixture to an oil-in water emulsion. The emulsionwas diluted with a further 15 parts water and heated at 80° C. for 3hours to effect chain extension polymerisation of the Si—H polymer andthe polyisobutylene.

The emulsion produced contained a linear silicone organic copolymer ofdynamic viscosity 8500 Pa.s at 0.01 Hz.

EXAMPLE 2

25 parts Si—H terminated polysiloxane, 2.5 parts allyl-terminatedpolyisobutylene and 0.35 parts catalyst were mixed as described inExample 1. 0.89 parts “Renex 30” (Trade Mark) polyethylene glycoltridecyl ether nonionic surfactant was added with stirring followed by 2parts water to form an oil-in-water emulsion. 1.33 parts sodium laurylether sulphate anionic surfactant was stirred in and the emulsion wasdiluted with 15 parts water. Polymerisation was carried out at 80° C.for 3 hours.

The emulsion produced contained a linear silicone organic copolymer ofdynamic viscosity 32300 Pas at 0.01 Hz.

EXAMPLES 3 TO 6

The procedure of Example 1 was followed using the Si—H terminatedpolydimethylsiloxanes and allyl-terminated polyisobutylenes listed inthe Table below (Epion 400A is believed to have molecular weight about10000), except that the amount of water added to dilute the emulsion was22 parts in each Example.

Si-H polymer Viscosity of Viscosity Polyisobutylene copolymer Example 3 12500 cPs 400A not measured Example 4  12500 cPs 200A 3400 Pa.s Example5 110000 cPs 400A 3350 Pa.s Example 6 110000 cPs 400A 2460 Pa.sThe viscosity quoted is the dynamic viscosity of the copolymer at 0.01Hz.

EXAMPLE 7

2.6 g “Epion 200A” allyl-endblocked polyisobutylene was diluted with 1.3g toluene and mixed with 0.05 g of the catalyst of Example 1 and thenwith 23.0 g Si—H terminated polydimethylsiloxane of viscosity 15000 cPs.Surfactants and water were stirred in as described in Example 1 to forman oil-in-water emulsion which was diluted and polymerised at 60° C. for3 hours to form a copolymer of molecular weight 640000 as measured bygas permeation chromatography (GPC).

1. A process for the preparation of an emulsion of a silicone organicblock copolymer in water, characterised in that a polydiorganosiloxanehaving terminal reactive groups (A), an organic material having terminalgroups (B) which are reactive with the groups (A) and a catalyst aremixed and then emulsified in water with a surfactant to form an emulsionand the resulting emulsion is subjected to conditions under which thereaction between groups (A) and (B) proceeds in the presence of thecatalyst, thereby forming a copolymer chain containing polysiloxaneblocks and blocks of organic material.
 2. A process for the preparationof an emulsion of a silicone organic block copolymer in water as claimedin claim 1, further characterised in that a polydiorganosiloxane havingterminal Si—H groups (A), an organic material having terminalaliphatically unsaturated groups (B) which are reactive with the Si—Hgroups (A) and a catalyst are emulsified in water with a surfactant toform an emulsion and the resulting emulsion is subjected to conditionsunder which the reaction between groups (A) and (B) proceeds in thepresence of the catalyst, thereby forming a copolymer chain containingpolysiloxane blocks and blocks of organic material.
 3. A processaccording to claim 2 wherein the organic material is a polymer having abackbone of carbon—carbon bonds.
 4. An emulsion of a silicone organiccopolymer in water, wherein the copolymer comprises polydiorganosiloxaneblocks and organic blocks and has a viscosity in the range 10 to 1000000Pa.s and a mean particle size of 0.3 to 1000 micrometers, wherein theorganic blocks are derived from an alpha-omega diene having 6 to 30carbon atoms.
 5. An emulsion of a silicone organic block copolymer inwater prepared by the process of claim
 1. 6. A process according toclaim 1, wherein the organic material is an alpha, omega-diene having 6to 30 carbon atoms.
 7. A process according to claim 1 wherein thecatalyst is a Pt^(iv) compound.
 8. A process according to claim 3,wherein the polymer is polyisobutylene.
 9. An emulsion of a siliconeorganic block copolymer in water prepared by the process of claim 1.